US Democrat Barack Obama's lead over Republican rival John McCain has grown to 12 points in the US presidential race, with crucial independent and women voters increasingly moving to his side, according to a Reuters/C-SPAN/Zogby poll released yesterday.

With less than two weeks before the Nov 4 election, Obama leads McCain 52 percent to 40 percent among likely voters in the latest three-day tracking poll, which had a margin of error of 2.9 points.

Obama has made steady gains over the last four days and has tripled his lead on McCain in the past week of polling.